The American left has long insisted that Democrats have cornered the diversity market, a talking point that, if not exactly true, has proven useful in portraying Republicans as anti-immigrant, anti-minority, anti-woman, anti-blac,k and anti-gay for decades. Nominating and electing the first black President was undoubtedly a particularly proud moment, one that seemed to confirm Democrats' position on the leading edge of diversity.

But maybe the diversity claim serves as nothing more than atonement for all those years Democrats identified as the "white man's party," or for their support of Southern slavery, the Ku Klux Klan, and Jim Crow laws. Or maybe, as the Rev. Wayne Perryman wrote in his book "Unfounded Loyalty," "Democrats didn't fall in love with black folks; they fell in love with the black vote."

Whether for reasons psychological or political, the left's decades-in-the-making diversity makeover has been effective. In modern political history, blacks, ethnic minorities, and women generally vote Democratic. But despite the cosmetic change that's come about on the left, when it comes to the ever-important diversity of thought, conservatism wins the day. And the now-expanding, now-contracting 2012 GOP presidential field is proof.

The American left has long insisted that Democrats have cornered the diversity market, a talking point that, if not exactly true, has proven useful in portraying Republicans as anti-immigrant, anti-minority, anti-woman, anti-blac,k and anti-gay for decades. Nominating and...